add a building switch: MayOverrideNewTab

if true, then still check manifest.json to learn
    whether new tab has been overridden,
so that a user can disable overriding easily
    (by deleting the line `"newtab": "pages/newtab.html"` in manifest.json).

This is for #42 .

Gulpfile.js

@@ -44,7 +44,7 @@ gulpPrint = gulpPrint.default || gulpPrint;
 createBuildConfigCache();
 var has_polyfill = !!(getBuildItem("BTypes") & BrowserType.Chrome)
     && getBuildItem("MinCVer") < 44 /* MinSafe$String$$StartsWith */;
-var has_newtab = getNonNullBuildItem("OverrideNewTab") > 0;
+var may_have_newtab = getNonNullBuildItem("MayOverrideNewTab") > 0;
 var es6_viewer = false;
 // es6_viewer = !(getBuildItem("BTypes") & BrowserType.Chrome) || getBuildItem("MinCVer") >= 52;
 const POLYFILL_FILE = "lib/polyfill.ts", NEWTAB_FILE = "pages/newtab.ts";
@@ -57,7 +57,7 @@ var CompileTasks = {
   lib: ["lib/*.ts"].concat(has_polyfill ? [] : ["!" + POLYFILL_FILE]),
   front: [["front/*.ts", has_polyfill ? POLYFILL_FILE : "!" + POLYFILL_FILE
             , "lib/injector.ts", "pages/*.ts"
-            , has_newtab ? NEWTAB_FILE : "!" + NEWTAB_FILE
+            , may_have_newtab ? NEWTAB_FILE : "!" + NEWTAB_FILE
             , "!pages/options*.ts", "!pages/show.ts"]
           , ["background/bg.d.ts", "content/*.d.ts"]
           , { inBatch: false }],
@@ -94,7 +94,7 @@ var Tasks = {
       , '!**/*.ts', "!**/*.js", "!**/tsconfig*.json"
       , "!test*", "!todo*"
     ];
-    has_newtab || arr.push("!" + NEWTAB_FILE.replace(".ts", ".*"));
+    may_have_newtab || arr.push("!" + NEWTAB_FILE.replace(".ts", ".*"));
     getBuildItem("BTypes") & BrowserType.Chrome || arr.push("!" + FILE_URLS_CSS);
     es6_viewer && arr.push("!" + VIEWER_JS);
     var has_wordsRe = getBuildItem("BTypes") & ~BrowserType.Firefox
@@ -132,7 +132,7 @@ var Tasks = {
       curConfig.push(getNonNullBuildItem("Commit"));
     }
     curConfig.push(getNonNullBuildItem("NDEBUG"));
-    curConfig.push(getNonNullBuildItem("OverrideNewTab"));
+    curConfig.push(getNonNullBuildItem("MayOverrideNewTab"));
     curConfig = JSON.stringify(curConfig);
     configFile = osPath.join(JSDEST, "." + configFile + ".build");
     var needClean = true;
@@ -236,7 +236,7 @@ var Tasks = {
       var oriManifest = readJSON("manifest.json", true);
       var res = ["**/*.js", "!background/*.js", "!content/*.js", "!front/vomnibar*", "!pages/options*"];
       has_polyfill || res.push("!" + POLYFILL_FILE.replace(".ts", ".*"));
-      has_newtab || res.push("!" + NEWTAB_FILE.replace(".ts", ".*"));
+      may_have_newtab || res.push("!" + NEWTAB_FILE.replace(".ts", ".*"));
       if (!has_dialog_ui) {
         res.push("!*/dialog_ui.*");
       }
@@ -292,7 +292,7 @@ var Tasks = {
     if (dialog_ui != null && !!dialog_ui !== has_dialog_ui && !dialog_ui) {
       manifest.options_ui && (manifest.options_ui.open_in_tab = true);
     }
-    if (getNonNullBuildItem("OverrideNewTab") <= 0) {
+    if (getNonNullBuildItem("MayOverrideNewTab") <= 0) {
       if (manifest.chrome_url_overrides) {
         delete manifest.chrome_url_overrides.newtab;
       }
@@ -408,10 +408,10 @@ gulp.task("locally", function(done) {
     CompileTasks.lib.length = 1;
     has_polyfill || CompileTasks.lib.push("!" + POLYFILL_FILE);
   }
-  var old_has_newtab = has_newtab;
-  has_newtab = getNonNullBuildItem("OverrideNewTab") > 0;
-  if (has_newtab != old_has_newtab) {
-    CompileTasks.front[0][4] = has_newtab ? NEWTAB_FILE : "!" + NEWTAB_FILE;
+  var old_has_newtab = may_have_newtab;
+  may_have_newtab = getNonNullBuildItem("MayOverrideNewTab") > 0;
+  if (may_have_newtab != old_has_newtab) {
+    CompileTasks.front[0][4] = may_have_newtab ? NEWTAB_FILE : "!" + NEWTAB_FILE;
   }
   es6_viewer = false;
   // es6_viewer = !(getBuildItem("BTypes") & BrowserType.Chrome) || getBuildItem("MinCVer") >= 52;
@@ -1049,7 +1049,7 @@ function getBuildItem(key, literalVal) {
   if (!cached) {
     if (key === "Commit") {
       cached = [literalVal, [safeJSONParse(literalVal), getGitCommit()]];
-    } else if (key === "OverrideNewTab") {
+    } else if (key === "MayOverrideNewTab") {
       if (!manifest.chrome_url_overrides || !manifest.chrome_url_overrides.newtab) {
         cached = buildOptionCache[key] = ["0", 0];
       }

background/main.ts

@@ -103,9 +103,10 @@ var Backend: BackendHandlersNS.BackendHandlers;
     if (!url) {
       delete args.url;
     } else if (!(type = Settings.newTabs_[url])) { /* empty */ }
-    else if (!Build.OverrideNewTab && type === Urls.NewTabType.browser) {
+    else if (!(Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_)
+        && Settings.CONST_ && type === Urls.NewTabType.browser) {
       delete args.url;
-    } else if (Build.OverrideNewTab && type === Urls.NewTabType.vimium) {
+    } else if (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_ && type === Urls.NewTabType.vimium) {
       args.url = Settings.cache_.newTabUrl_f;
     }
     Build.BTypes & BrowserType.Edge && (!(Build.BTypes & ~BrowserType.Edge) || OnOther === BrowserType.Edge) &&
@@ -2266,7 +2267,7 @@ Are you sure you want to continue?`);
           return;
         }
         sender.f = Frames.Flags.userActed;
-      } else if (Build.BTypes & BrowserType.Firefox && Build.OverrideNewTab && type === PortType.CloseSelf) {
+      } else if (Build.BTypes & BrowserType.Firefox && (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_) && type === PortType.CloseSelf) {
         if (tabId >= 0 && !sender.i) {
           removeTempNewTab(tabId, port);
         }
@@ -2301,7 +2302,7 @@ Are you sure you want to continue?`);
       });
     }
     sender.s = status;
-    if (Build.BTypes & BrowserType.Firefox && Build.OverrideNewTab) {
+    if (Build.BTypes & BrowserType.Firefox && (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_)) {
       (port as chrome.runtime.Port).sender.tab = null as never;
     }
     port.onDisconnect.addListener(OnDisconnect);
@@ -2353,7 +2354,7 @@ Are you sure you want to continue?`);
               : cPort ? cPort.s.t : TabRecency_.last_;
         }
         framesForOmni.push(port);
-        if (Build.BTypes & BrowserType.Firefox && Build.OverrideNewTab) {
+        if (Build.BTypes & BrowserType.Firefox && (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_)) {
           (port as chrome.runtime.Port).sender.tab = null as never;
         }
         port.onDisconnect.addListener(OnOmniDisconnect);
@@ -2397,7 +2398,7 @@ Are you sure you want to continue?`);
       url: "",
       incognito: false
     };
-    if (!(Build.BTypes & BrowserType.Firefox && Build.OverrideNewTab)) {
+    if (!(Build.BTypes & BrowserType.Firefox && (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_))) {
       sender.tab = null as never;
     }
     return (port as Writeable<Port>).s = {

background/settings.ts

@@ -471,6 +471,7 @@ v.m|v\\:math: vimium://math\\ $S re= Calculate
     Exclusions: "/background/exclusions.js",
     InjectEnd_: "content/injected_end.js",
     NewTabForNewUser_: "pages/options.html#!newTabUrl",
+    OverrideNewTab_: !!Build.MayOverrideNewTab,
     OptionsPage_: "pages/options.html", Platform_: "browser",
     baseCSS: "vimium.min.css",
     exclusionTemplate: "exclusions.html",
@@ -558,23 +559,26 @@ if (Build.BTypes & BrowserType.Firefox && !Build.NativeWordMoveOnFirefox
     (payload_ as Writeable<typeof payload_>).browser_ =
         (settings.omniPayload_ as Writeable<VomnibarPayload>).browser_ = OnOther;
   }
+  if (Build.MayOverrideNewTab) {
+    const overrides = ref.chrome_url_overrides, hasNewTab = overrides && overrides.newtab;
+    Settings.CONST_.OverrideNewTab_ = !!hasNewTab;
+    if (hasNewTab) {
+      ref3[func(hasNewTab)] = Urls.NewTabType.vimium;
+    }
+  }
   (defaults as SettingsWithDefaults).newTabUrl = (Build.BTypes & ~BrowserType.Chrome
       && (!(Build.BTypes & BrowserType.Chrome) || OnOther !== BrowserType.Chrome))
-      ? CommonNewTab : Build.OverrideNewTab ? obj.NtpNewTab_ : ChromeNewTab;
+      ? CommonNewTab : (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_) ? obj.NtpNewTab_ : ChromeNewTab;
   // note: on firefox, "about:newtab/" is invalid, but it's OKay if still marking the URL a NewTab URL.
   /** Note: .vimium and .browser should never exist in the same time
-   * use {@link #Build.OverrideNewTab} to decide which one
+   * use {@link #Build.MayOverrideNewTab} and {@link #Settings.CONST_.OverrideNewTab_)} to decide which one
    * required by {@link main.ts#tabsCreate}
    */
-  ref3[CommonNewTab] = ref3[CommonNewTab + "/"] = Build.OverrideNewTab
+  ref3[CommonNewTab] = ref3[CommonNewTab + "/"] = (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_)
       ? Urls.NewTabType.vimium : Urls.NewTabType.browser;
   (Build.BTypes & ~BrowserType.Chrome && (!(Build.BTypes & BrowserType.Chrome) || OnOther !== BrowserType.Chrome)) ||
-  (ref3[ChromeNewTab] = ref3[ChromeNewTab + "/"] = Build.OverrideNewTab
+  (ref3[ChromeNewTab] = ref3[ChromeNewTab + "/"] = (Build.MayOverrideNewTab && Settings.CONST_.OverrideNewTab_)
       ? Urls.NewTabType.vimium : Urls.NewTabType.browser);
-  if (Build.OverrideNewTab) {
-    type Overridden = EnsureNonNull<typeof ref.chrome_url_overrides>;
-    ref3[func((ref.chrome_url_overrides as Overridden).newtab)] = Urls.NewTabType.vimium;
-  }
   obj.GlobalCommands_ = (<Array<kShortcutNames | kShortcutAliases & string>> Object.keys(ref.commands || {})
       ).map(i => i === kShortcutAliases.nextTab1 ? kShortcutNames.nextTab : i);
   obj.VerCode_ = ref.version;

pages/loader.ts

@@ -23,19 +23,22 @@ window.chrome && chrome.runtime && chrome.runtime.getManifest && (function () {
     head.appendChild(scriptElement);
     scripts.push(scriptElement);
   }
+  interface BgWindow extends Window { Settings: typeof Settings; }
   scripts[scripts.length - 1].onload = function (): void {
     for (let i = scripts.length; 0 <= --i; ) { scripts[i].remove(); }
     const dom = (window as {} as {VDom?: typeof VDom}).VDom;
     dom && (dom.allowScripts_ = 0);
-    if (Build.BTypes & BrowserType.Firefox && Build.OverrideNewTab
+    let bg: BgWindow;
+    if (Build.BTypes & BrowserType.Firefox && Build.MayOverrideNewTab
+        && (bg = chrome.extension.getBackgroundPage() as BgWindow)
+        && bg.Settings.CONST_.OverrideNewTab_
         && location.pathname.indexOf("newtab") >= 0) {
       setTimeout(function (): void {
         const hud = (window as {} as {VHud?: VHUDTy}).VHud;
         hud && hud.tip_("Not allowed to open the target new tab URL", 2560);
       }, 100);
     }
   };
-  interface BgWindow extends Window { Settings: typeof Settings; }
   if (location.pathname.toLowerCase().indexOf("options") < 0) {
     const bg = chrome.extension.getBackgroundPage() as BgWindow;
     if (bg && bg.Backend) {

pages/options.ts

@@ -404,7 +404,7 @@ interface AdvancedOptBtn extends HTMLButtonElement {
     bgSettings_.broadcast_(req);
   }
 
-  if (!Build.OverrideNewTab) {
+  if (!(Build.MayOverrideNewTab && bgSettings_.CONST_.OverrideNewTab_)) {
     $<EnsuredMountedElement & HTMLElement>("#focusNewTabContent").parentElement.parentElement.parentElement.remove();
     $<EnsuredMountedElement & HTMLElement>("#newTabUrlRefer").remove();
   }

pages/options_checker.ts

@@ -81,7 +81,7 @@ let keyMappingChecker_ = {
 Option_.all_.keyMappings.checker_ = keyMappingChecker_;
 keyMappingChecker_ = null as never;
 
-if (Build.OverrideNewTab) {
+if (Build.MayOverrideNewTab && bgSettings_.CONST_.OverrideNewTab_) {
 Option_.all_.newTabUrl.checker_ = {
   check_ (value: string): string {
     let url = (<RegExpI> /^\/?pages\/[a-z]+.html\b/i).test(value)

types/build/index.d.ts

@@ -9,7 +9,7 @@ declare const enum Build {
   NoDialogUI = 0,
   NativeWordMoveOnFirefox = 1,
   PContentSettings = 1,
-  OverrideNewTab = 1,
+  MayOverrideNewTab = 1,
   DetectAPIOnFirefox = 1,
 }
 declare const enum BuildStr {